I found shaking for more than half a minute to be a pain and worry about spilling the wort. I thought of a way that seems much easier last night. Only tested with water so far. Since I take my wort down a floor to the basement, I can use a bungie cord to strap my pail into a hand truck, put an airlock in the lid (sacrificial since it might splash out some?) and then all I have to do is tip the hand truck and roll it back and forth vigorously to slosh it around good. It seems physically easy to do for an extended period and I don't have to worry about dropping it. For a carboy I would probably use more than one strap and a solid bung with something else to make sure it didn't fall out (foil?).
I haven't done extensive testing with wort aeration yet, but I have generally been trying to get some air mixed in for some time since I heard about it.